メカニカル拡大システムを用いた短スパンひずみ計の開発

Abstract

既存の坑道を利用することを前提とした，設置が簡易で比較的経費のかからない短スパンひずみ計の開発を試みた。長スパンの基準尺ひずみ計と同等の感度を得るために石井等が開発したメカニカル拡大システムを用いた。試作の円筒形短スパンひずみ計を逢坂山観測所坑道内の岩盤内に固着し，観測を開始した。潮汐ひずみ変動や地震が記録でき，伸縮計として利用できることが確かめられた。

We developed a short span strainmeter using a mechanical magnification system. The cylinder of the short span strainmeter was installed into hard rock about 2 m in depth in a tunnel at Osakayama observatory. Observation of the short span strainmeter was started from 31 Jan., 2005. As compared with the long span strainmeter(E3) with the same orientation, we confirmed that the short span strainmeter could obtain records of tidal changes and strain seismograms of the northern Sumatra earthquake similar to records of the E3. We were certain that the short span strainmeter could be useful for observing ground strains. We will plan the next manufacture of the short span strainmeters with three components in the cylinder.